1. Field of the Invention
The present invention relates to a vehicular rotary machine which has a starting motor.
2. Description of the Related Art
A car or a motor cycle usually has a separate starter motor for starting an engine and a separate generator for supplying a battery and electric accessories of a vehicle with electric power. Therefore, they must be mechanically coupled with the crankshaft and electrically connected to the battery separately, resulting in a complex structure and in increase of the size.
JPU 60-34761 discloses a tandem unit of a starter motor and an alternator for a vehicle, in which the rotary shaft of the starter motor and a rotary shaft of an accessory such as the alternator are coupled by a clutch-roller-type overrunning clutch so that the rotary shaft of the starter motor can drive the crankshaft via the overrunning clutch and the rotary shaft of the accessory. The clutch-roller-type overrunning clutch has a drive member, a driven member, clutch rollers in a wedge-groove formed between the drive and driven members. When the driven member is rotated faster than the driving member, the clutch roller is moved in a direction to increase the gap between the roller and the groove. Such an overrunning clutch is usually installed in the starter motor to prevent the accessory's shaft, driven member and the driving member from being driven by the crankshaft.
In the above publication, when the engine starts and, consequently, the crankshaft and the alternator's shaft rotates at a high speed, the driven member of the overrunning clutch rotates at such a high speed for a long time period. As a result, the lubrication between the peripheral surface of the driven member and the clutch roller in contact with the peripheral surface becomes rough and the life time of the overrunning clutch is shortened. This is a severe problem when a speed reduction mechanism is installed between the overrunning clutch and the crankshaft to make a starter motor compact by increasing the speed of rotation thereof.